1. Field of the Invention
The present invention relates to an inspecting method of a color filter for inspecting the coloring density of a coloring portion of the color filter at high speed with high accuracy, and a manufacturing method of the color filter utilizing this inspecting method.
2. Related Background Art
A color filter constituting a liquid crystal display unit is generally constructed by arranging coloring portions colored in red (R), green (G) and blue (B) as three primary colors of light on a transparent substrate. A dyeing method, a pigment dispersing method, an electrodepositing method, etc. are conventionally used as a manufacturing method of the color filter. However, an ink jet system simple in process and economically advantageous has recently been used.
When a coloring portion is formed by using the ink jet system, ink is individually given to predetermined areas. Therefore, unlike the other systems, a problem of uneven coloring is caused by the density distribution in the coloring portions. A defect of the uneven coloring is more than visually recognizable even when this density distribution is only several %, depending on a color of the coloring portion. Accordingly, in a manufacturing process of the color filter using the ink jet system, it is required that these color irregularities are discriminated with high accuracy and an ink amount to be given is further controlled on the basis of the results of this discrimination.
In an inspection of the color irregularities of the color filter, generally, an absolute value of the coloring density is a problem as well as the color irregularities. Therefore, a reference light amount is adjusted. In the reference light amount adjustment, a transmitting light amount is adjusted in a transparent (no light shielding layer such as a black matrix, etc. exists) uncoloring portion within a non-display area. An amount of incident light entering to a CCD camera at an adjusting time of this reference light amount reaches two to five times an amount of incident light entering to the CCD camera when the transmitting light amount of the coloring portion is measured. Therefore, when a light amount of the light source is set such that this light amount is equal to or smaller than a light amount providing a full output of the CCD camara at the time of the reference light amount adjusting, only a light amount of 1/5 to 1/2 times this set light amount is entered to the CCD camera at a measuring time of the coloring portion. Therefore, a reduction in S/N is caused by a dark electric current of the CCD, etc. In particular, in the inspection of the uneven coloring in the color filter, it is necessary to discriminate the amount of incident light entered from a transmitting light amount equal to or smaller than 1% in the coloring portion of the same color. Therefore, it is necessary to avoid this reduction in S/N. To avoid this reduction, it is considered that the light amount of the light source at the measurement time of the coloring portion is increased.
However, when the light amount of the light source is adjusted, the light amount is unstable for some time after the adjustment. As described above, it is necessary to discriminate the coloring density distribution at a level of several %. Accordingly, such an unstable light amount just after the adjustment of the light amount causes an error in measurement. Therefore, when the light amount is adjusted, it is necessary to take time until the light amount is stabilized, which is an obstacle in improving efficiency by shortening an inspecting time.